As a rule, forcibly steered vehicles comprise a hydraulic master cylinder to receive the steering movement and a slave cylinder which steers a forcibly steered wheel. With trailers, for example, for agricultural purposes, the master cylinder, as a rule, is placed with one end coupled to the chassis of the trailer and the other end, located laterally, next to the coupling of the trailer to the drawbar of the tractor. When driving through curves, wheels of one axle of the trailer are steered according to the movement of the tractor with respect to the trailer, which advantageously results in better curve driving behavior and reduced tire wear. With three-axle vehicles, two axles are steered.
However, for example, as a result of different steering points on different tractors or when changing the tire sizes of the tractor, situations are conceivable in which the master cylinder undergoes a greater steering movement than the slave cylinder is able to execute. Relatively high pressures thereby arise in the hydraulic system of the forced steering device, which can lead to damage to the parts of the hydraulic system.
DE 41 34 501 A describes a truck in which a trailer control axle is forcibly adjusted by a hydraulic cylinder. The hydraulic cylinder can be connected via a valve to a pressure source, whose pressure is limited by a pressure limiting valve. A limitation of the pressure takes place in the controlled hydraulic cylinder, but with a steering system which is basically constructed differently. The teaching of this publication cannot be transferred to a forced steering of the initially mentioned type.